FIVE ILLINOIAN MOLLUSCAN FAUNAS FROM THE SOUTHERN GREAT PLAINS BY Barry B. Miller Department of Geology, Kent State University Kent, Ohio, U. S. A. MALA COLOGIA Vol. 4, No. 1, p 173-260 Reprinted MALACOLOGIA, 1966, 4(1): 173-260 FIVE ILLINOLAN MOLLUSCAN FAUNAS FROM THE SOUTKERN GREAT PLAINS^,^ Barry B. Miller Department of Geology, Kent State University Kent, Ohio, U. S. A. ABSTRACT The mollusks from 5 late Cenozoic (Illinoian) assemblages in the southwestern Kansas-northwestern Oklahoma area: the Berends local fauna, of Beaver County, Oklahoma; the Doby Springs local fauna, of Harper County, Oklahoma; and the Adams , Butler Spring and Mount Scott local faunas, of Meade County, Kansas, are listed. A summary of information consisting of geologic range, distribution and ecology is given for all of the mollusks in the Mount Scott and Doby Springs local faunas, and for previously unreported species from the Berends, Adams and Butler Spring local faunas. Taxonomic changes include assignment of Promenetus exacuous and Pro- menetus kansasensis to a single species complex. There is no satisfactory way of separating these 2 uspecies" in Recent and fossil populations that contain in- dividuals with both riblet and non-riblet type surface ornamentation. The riblet type is designated Promenetus exacuous form kansasensis and the non-riblet form Promenetus exacuous form exacuous. Interpretation of these molluscan assemblages is predicated on the assumptions that climatic factors are the primary agents controlling the distribution of non- marine mollusks; that fossil shells similar to those of living species represent the same species and were subject to the same limiting factors; and that the areas in the Great Plains presently containing associations of mollusks most similar to those found in these fossil assemblages, probably closely simulate the climatic conditions that existed at the time these fossils lived. Recon- struction of local habitat and climatic conditions under which these faunas lived has been based on a synthesis of information obtained from the fossil mollusks, pollen and vertebrates. In no case have interpretations based on the mollusks conflicted with conclusions reached independently from other fossil data. The 5 Illinoian assemblages show compositional differences that are probably related to climatic changes during the nlinoian. The relatively large number of species with predominantly northern distributions, together with the low repre- sentation of exclusively southern faunal elements, indicate that the Doby Springs local fauna represents the coolest of the assemblages studied, and probably lived during maximum nlinoian glaciation. The Mount Scott local fauna contains a greater number of species with southern distributions than any of the other faunas studied, suggesting that it represents the warmest of these Illinoian faunas. There is no evidence inthis area indicatingthat these faunas lived during more than one substage. Assuming that the transition from maximum glacial conditions, represented by the Doby Springs local fauna, towards warmer inter- '~ontrl~utionNo. 2, Department of Geology, Kent State university. Research supported (in part) by National Science Foundation grant G- 5635. 2~daptedfrom a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the University of Michigan. I74 B. B. MILLER glacial conditions, represented by the Mount Scott local fauna, was unidirectional, then the climatic conditions implied by the Adams and Butler Spring assemblages must have occurred sometime between the time represented by the Doby Springs and Mount Scott local faunas. The first and last appearances of molluscan species and climatic implications of the Berends local fauna suggests that this assemblage is probably the oldest of these 5 Lllinoian faunas. The Berends assemblage contains 45 species of mollusks, 15 of which are new to this local fauna. One species, Sphaerium securis, represents the first fossil occurrence of this species from the southern Plains. This fauna lived in and around the margin of a small, shallow lake where the vegetation cover probably consisted mainly of conifers, grasses and composites, with only scattered patches of deciduous trees. The climate at the time this assemblage lived was probably similar to that presently occurring in the northeastern Neb- raska-northwestern Iowa region of the Great Plains. The Doby Springs local fauna contains 59 species of mollusks, one of which, Veertigo elatior is recorded for the first time as a fossil in the southern Plains. The mollusks indicate the existence of a cool, upstream lake, bordered by a marsh containing cattails, sedges and scattered deciduous and coniferous trees, which graded into a better drained shrub and tree community further back from the lake. The inferred former local climate combined shorter, cooler summers, with winters that were slightly cooler and longer than those presently prevailing in this region. The Adams molluscan assemblage contains 22 species, one of which, Lasmi- gona complanata is first recorded as fossil from this area. The medium to coarse, cross-bedded sands from which the fauna was recovered, together with the occurrence of molluscan species requiring continuity of aquatic habitat, in- dicate the existence of a stream. The presence of only 1 woodland species among the terrestrial gastropods suggests that there was only a thin covering of trees and shrubs. The climate probably combined winters perhaps no more severe than those presently occuring in northeastern Nebraska, with cooler, more moist summers, similar to those in the Dakotas and eastern Montana. There are 54 species of mollusks in the Butler Spring local fauna, one of which, Ligumia cf recta, is new to the southern Great Plains. This fauna lived in or near a medium sized river, with a slow to moderate current and a probable depth of several feet. There were scattered groups of trees along the river, but the predominant vegetation consisted of grasses and shrubs. The climate suggested by the assemblage consisted of cooler summers, similar to those now occurring in the eastern North Dakota region. Winters were probably no more severe than those in northcentral Nebraska. The Mount Scott molluscan fauna, containing 63 species, is the largest such assemblage known from the southern Plains. It contains the only fossil record of Zonitoides nitidus from the Great Plains. Sedimentary and paleontologic evi- dence indicate that 5 major habitat associations are represented. The climate at that time probably combined summers similar to those now occurring in the Lake Okoboji region of northwest Iowa, with winters no more severe than those in the northeast Kansas-southeast Nebraska area. CONTENTS Page Page INTRODUCTION ............. .I75 Introduction .............. .I76 Berends Local Fauna .........I77 FAUNAL DISCUSSION ......... .I76 Doby Springs Local Fauna ......I81 FIVE ILLINOIAN FAUNAS 175 Contents (cont.) Page Page Adams Local Fauna . .I86 Family Lymnaeidae. ,225 Butler Spring Local Fauna . .I88 Superfamily Ancyloidea. .227 Mount Scott Local Fauna . .I89 Family Planorbidae. .227 Summary of Illinoian molluscan Family Ancylidae . .236 I - faunas . .212 Family Physidae . .237 Order Stylommatophora . .240 SYSTEMATIC DISCUSSION . .216 Superfamily Cionelloidea . .240 e Class Pelecypoda . .217 Family Cionellidae . .240 Order Prionodesmacea . .217 Superfamily Pupilloidea . .240 Family Unionidae . .217 Family Strobilopsidae . .240 Order Teleodesmacea . 220 Family Pupillidae . .240 Family Sphaeriidae . .220 Family Valloniidae . .246 Class Gastropoda . , . .220 Superfamily Succineoidea . .247 Subclass Prosobranchia . .224 Family Succineidae . .247 Order Mesogastropoda . .224 Superfamily Endodontoidea . .247 Superfamily Valvatoidea . .224 Family Endodontidae . .247 Family Valvatidae . .224 Superfamily Zonitoidea . .249 Superfamily Rissoidea. .225 Family Limacidae . .249 Family Hydrobiidae . .225 Family Zonitidae . .249 Subclass Euthyneura . .225 Superfamily Polygyroidea . .252 Order Basommatophora . .225 Family Polygyridae . .252 Superfamily Ellobioidea . .225 ACKNOWLEDGEMENTS . .252 Family Ellobiidae. .225 . Superfamily Lymnaeoidea. .225 REFERENCES . .253 INTRODUCTION intervals have been recognized in the Meade County area, which are believed Under supervision of Claude W. to correlate withthe Nebraskan-Kansan- Hibbard, field parties from the Uni- Illinoian-Wisconsin glacial and Aftonian- versity of Kansas (1936-1946) and Uq- Yarmouth-Sangamon interglacial stages versity of Michigan (from 1947 onwards) in the classical Mississippi Valley have been engaged in an intensive study sequence. of the late Cenozoic fossils and strati- The washing technique developed by graphic sequence of the southwest Hibbard (1949b) has made possible the Kansas-northwest Oklahoma area. recovery of extensive collections of During the 27-year period from 1936- fossils which have included ostracods, 1963, 13 Pleistocene faunas ranging in mollusks, fishes, amphibians, reptiles, age from Aftonian to Wisconsin, have birds and mammals. Detailed study of been studied (see Fig. 1, and summaries the pollen associated with these faunas in Taylor, 1960; Hibbard & Taylor, has recently been undertaken by Kapp 1960). Correlation of the Pleistocene (1965). Some of these groups have sequence in this area with that of the barely been studied, while others have glaciated region to the north and north- been fairly intensively described and east, is based on the